In such a double clutch, the arrangement in which both partial clutches K1 and K2 are open (“normally open”) exists and are closed at least by means of an actuation device. In this arrangement, actuation forces necessary and normally alternately applied to press the clutch closed must be applied in the same direction. These actuation forces must be supported on a bearing on the crankshaft or in the transmission. If one assumes that the partial clutch K1 is initially open and the partial clutch K2 is initially closed, then the total actuation force of the arrangement is equal to the actuation force of the partial clutch K2. If overlapped shifting is subsequently carried out to close the partial clutch K1 and open the partial clutch K2, then the actuation force of partial clutch K1 increases and the actuation force of partial clutch K2 decreases. The total actuation force nonetheless essentially remains the same. In the final state, the partial clutch K1 is closed and the partial clutch K2 opened. The total actuation force then corresponds to the actuation force of partial clutch 1. The total actuation force in this arrangement therefore remains essentially equally high over the entire period.
In an alternative formation of the double clutch, an arrangement exists in which the partial clutch K1 in the initial state is closed (“normally closed”) and is at least pressed open via an actuation device, and that the partial clutch K2 in the initial state is open (“normally open”) and is pressed closed via at least an actuation device. Two different states arise in such an arrangement: When the partial clutch K1 is closed and the partial clutch K2 is open, no actuation force is required. In order to open the partial clutch K1 and close the partial clutch K2 on the other hand, two actuation forces are required. In this case, both actuation forces add up and yield a high axial force on the bearing.
In truck applications that can feature torque up to 3,300 . . . 3,500 Nm, actuation forces of up to 12,400 . . . 15,000 N occur In truck applications, the arrangements described above would have to support the very large actuation forces correspondingly occurring on the crankshaft and on transmissions bearings. Target must consequently be to minimize the necessary actuation forces and particularly the sum of both actuation forces in order to reduce the dimension of the bearing and avoid all associated changes in the housing.